The subject-matter of the invention is a composition for the oxidation dyeing of keratinous fibres, in particular human keratinous fibres, such as hair, comprising, as coupler, at least one thiazoloazole S-oxide compound and/or at least one thiazoloazole S,S-dioxide compound and at least one oxidation base.
It is known to dye keratinous fibres and in particular human hair with dyeing compositons comprising oxidation dye precursors, in particular ortho- or para-phenylenediamines, ortho- or para-aminophenols, or heterocyclic compounds, generally known as oxidation bases. Oxidation dye precursors or oxidation bases are colourless or weakly coloured compounds which, in combination with oxidizing products, can give rise, by an oxidative coupling process, to coloured and colouring compounds.
It is also known that it is possible to vary the shades obtained with these oxidation bases by combining them with couplers or colouring modifers, the latter being chosen in particular from aromatic meta-diamines, meta-aminophenols, meta-diphenols and certain heterocyclic compounds, such as indole compounds.
The variety of the molecules involved as oxidation bases and couplers makes it possible to obtain a rich palette of colours.
The so-called xe2x80x9cpermanentxe2x80x9d colouring obtained by virtue of these oxidation dyes has, however, to satisfy a certain number of requirements. Thus, it must be without disadvantage toxicologically and it must make it possible to obtain shades with the desired intensity and behave well in the face of external agents (light, bad weather, washing, permanent waving, perspiration or rubbing).
The dyes must also make it possible to cover white hair and, finally, be as non-selective as possible, that is to say make it possible to obtain the smallest possible differences in colouring along the same keratinous fibre, which can in fact be differently sensitized (i.e. damaged) between its tips and its root.
The Applicant Company has not just discovered that it is possible to obtain powerful novel dyes, which are not very selective, which are particularly resistant and which are capable of generating intense colourings in varying shades, by using, as couplers, thiazoloazole S-oxide and/or thiazoloazole S,S-dioxide compounds in the presence of an oxidation base.
This discovery forms the basis of the present invention.
The subject-matter of the invention is a composition for the oxidation dyeing of keratinous fibres and in particular of human keratinous fibres, such as hair, charactierized in that it comprises, in a medium appripriate for dyeing:
as coupler, at least one thiazoloazole S-oxide compound and/or at least one thiazoloazole S,S-dioxide compound of formula (I) and/or at least one of their addition salts with an acid: 
in which:
R1 represents a hydrogen atom; a halogen atom, such as bromine, chlorine or fluorine; an alkoxy radical (such as, for example: methoxy, ethoxy, propyloxy, benzyloxy, methoxyethoxy, phenoxyethoxy, 2-cyanoethoxy, phenethyloxy, p-chlorobenzyloxy or methoxyethylcarbamoylmethoxy); an aryloxy radical (such as, for example: phenoxy, 4-methoxyphenoxy, 4-nitrophenoxy, 4-cyanophenoxy, 4-methanesulphonamidophenoxy, 4-methanesulphonylphenoxy, 3-methylphenoxy or 1-naphthyloxy); an acyloxy radical (such as, for example: acetoxy, propanoyloxy, benzoyloxy, 2,4-dichlorobenzoyloxy, ethyoxyoxaloyloxy, pyruvoyloxy, cinnamoyloxy or myristoyloxy); an arylthio radical (such as, for example: phenylthio, 4-carboxyphenylthio, 2-ethoxy-5-tert-butylphenylthio, 2-carboxyphenylthio or 4-methanesulphonylphenylthio); an alkylthio radical (such as, for example: methylthio, ethylthio, propylthio, butylthio, 2-cyanoethylthio, benzylthio, phenethylthio, 2-(diethylamino)ethylthio, ethyoxyethylthio or phenoxyethylthio); a heteroarylthio radical (such as, for example: 5-phenyl-2,3,4,5-tetrazolythio or 2-benzothiazolylthio); a heteroaryloxy radical (such as, for example: 5-phenyl-2,3,4,5-tetrazolyloxy or 2-benzothiazolyloxy); a thiocyano radical; an alkyloxythiocarbonylthio radical (such as dodecyloxythiocarbonylthio); a sulphonamido radical (such as benzenesulphonamido or N-ethyltoluenesulphonamido); a pentafluorobutanamido radical; a 2,3,4,5,6-pentafluorobenzamido radical; a pyrazolyl radical; an imidazolyl radical; a triazolyl radical; a tetrazolyl radical; a benzimidazolyl radical; a 1-benzyl-5-ethoxy-3-hydantoinyl radical; a 1-benzyl-3-hydantoinyl radical; a 5,5-dimethyl-2,4-dioxo-3-oxazolidinyl radical; a 2-oxo-1,2-dihydro-1-pyridinyl radical; an alkylamido radical; an arylamido radical; an NRIIIRIV radical with RIII and RIV, which are identical or different, representing a C1-C4 alkyl or a C1-C4 hydroxyalkyl; a carboxyl radical; an alkoxycarbonyl radical; an alkyloxycarbonylamino radical; an aryloxcarbonylamino radical; a sulphonyloxy radical, such as methanesulphonyloxy; an alkoxycarbonyloxy radical, such as methoxycarbonyloxy or ethoxycarbonyloxy; or an aryloxycarbonyloxy radical, such as phenyloxycarbonyloxy;
Za, Zb and Zc represent, independently of one another, a nitrogen atom or else a carbon atom carrying an R2, R3 or R4 radical; provided that:
when Za denotes a carbon atom carrying an R2 radical, then Zb represents a nitrogen atom and Zc denotes a carbon atom carrying an R3 radical;
when Za denotes a nitrogen atom, then Zb represents a carbon atom carrying an R4 radical and Zc denotes a nitrogen atom;
R2, R3 and R4 represent, independently of one another, a hydrogen atom; a linear or branched C1-C20 alkyl radical optionally substituted by 1 or 2 R radicals chosen from the group consisting of halogen, nitro, cyano, hydroxyl, alkoxy, aryloxy, amino, alkylamino, acylamino, carbamoyl, sulphonamido, sulphamoyl, imido, alkylthio, arylthio, aryl, alkoxycarbonyl or acyl; an aryl radical (such as phenyl or naphthyl) optionally subsititued by 1 or 2 R radicals as defined above; a halogen atom (such as bromine, chlorine or fluorine); an acyl radical; a sulphonyl radical; a sulphinyl radical; a phosphonyl radical; a carbamoyl radical; a sulphamoyl radical; a cyano radical; an amino radical; an alkylamino radical; an acylamino radical; an alkylthio radical; an arylthio radical; an acyloxy radical; a carbamoyloxy radical; a sulphonamido radical; an imido radical; a uredido radical; a sulphamoylamino radical; an alkoxycarbonylamino radical; an aryloxycarbonylamino radical; an alkoxycarbonyl radical; an aryloxycarbonyl radical; a carboxyl radical; a nitro radical; a sulphonyl radical; a hydroxyl radical; a mercapto radical; or a trifluoromethyl radical;
n has the value 1 or 2;
and at least one oxidation base.
The addition salts with an acid of the compounds of the invention can be chosen in particular from hydrochlorides, hydrobromides, tartrates, tosylates, benzenesulphonates, sulphates, lactates and acetates.
Preference is given, among the R1 radicals of the formula (I) defined above, to the radicals chosen from the group consisting of a hydrogen atom; a C1-C4 alkoxy radical; a phenoxy radical; a phenoxy radical substituted by a halogen atom, a C1-C4 alkyl, a carboxyl, a trifluromethyl group or an acyloxy, benzyloxy or C1-C4 alkylthio radical; a phenylthio radical; a phenylthio radical substituted by a halogen atom, a C1-C4 alkyl, a carboxyl or a trifluoromethyl group; a C1-C4 alkylamido radical; a phenylamido radical; an NRIIIRIV radical with RIII and RIV, which are identical or different, representing a C1-C4 alkyl or a C1-C4 hydroxyalkyl; a carboxyl radical; a C1-C4 alkoxycarbonyl radical or a halogen atom, such as chlorine or bromine.
More particularly still, preference is given to the R1 radicals chosen from the group consisting of hydrogen, chlorine, ethoxy, phenoxy, benzyloxy, acyloxy, acetamido and dimethylamino.
Preference is given, among the R2, R3 or R4 radicals of the formula (I), to the radicals chosen from the group consisting of a hydrogen atom; a linear or branched C1-C4 alkyl radical; an aryl radical; an aryl radical substituted by a halogen atom, a methoxy radical, a nitro group, a cyano group, a trifluromethyl group or an amino group; a cyano radical; a nitro radical; an acylamino radical; an arylamino radical; an alkylthio radical, such as methylthio or ethylthio; an arylthio radical, such as phenylthio; a carbamoyl radical, such as N-ethylcarbamoyl; a sulphonyl radical, such as methylsulphonyl; an alkoxycarbonyl radical, such as methoxycarbonyl or ethyoxycarbonyl; an aryloxycarbonyl radical, such as phenoyxcarbonyl; or an acyl radical, such as acetyl or propionyl.
More particularly still, preference is given to the R2, R3 or R4 radicals of the formula (I) chosen from the group consisting of a hydrogen atom; a linear or branched C1-C4 alkyl radical (such as methyl, ethyl or isopropyl); a phenyl radical; or a phenyl radical substituted by a halogen atom, a methoxy radical, a nitro group, a cyano group, a trifluoromethyl group or an amino group.
Mention may be made, among the preferred compounds of formula (I) of the invention, of those chosen from the group consisting of:
i) the compounds of following formula (Ia): 
in which R1 represents a hydrogen or chlorine atom; R2 and R3 denote, independently of one another, a hydrogen atom, a methyl radical, an ethyl radical or a phenyl radical; and n has the value 1 or 2,
ii) the compound of following formula (Ib): 
in which R1 represents a hydrogen or chlorine atom; R4 denotes a hydrogen atom, a methyl radical, an ethyl radical, a phenyl radical, a trifluoromethyl radical or a cyano radical; and n has the value 1 or 2.
Mention may be made, among the particularly preferred compounds of formula (I) of the invention, of those chosen from the group consisting of:
3-nitro-5-methyl-7-oxothiazolo[2,3-e]imidazole sulphoxide;
3-nitro-5-methyl-7-oxothiazolo[2,3-e]imidazole S,S-dioxide;
3-amino-5-methyl-7-oxothiazolo[2,3-e]imidazole sulphoxide;
3-amino-5-methyl-7-oxothiazolo[2,3-e]imidazole S,S-dioxide;
3-amino-5-phenyl-7-oxothiazolo[2,3-e]imidazole sulphoxide;
3-nitro-5-phenyl-7-oxothiazolo[2,3-e]imidazole sulphoxide;
3-nitro-5-methyl-7-oxothiazolo[2,3-e]imidazole S,S-dioxide;
3-amino-5-phenyl-7-oxothiazolo[2,3-e]imidazole S,S-dioxide;
3-phenyl-5-methyl-7-oxothiazolo[2,3-e]imidazole sulphoxide.
Mention may be made, among the particularly preferred compounds of formula (I) of the invention, of those chosen from the group consisting of:
4-methyl-7-oxothiazolo[2,3-b]triazole sulphoxide;
4-ethyl-7-oxothiazolo[3,2-b]triazole sulphoxide;
4-isopropyl-7-oxothiazolo[3,2-b]triazole sulphoxide;
4-propyl-7-oxothiazolo[3,2-b]triazole sulphoxide;
4-trifluoromethyl-7-oxothiazolo[2,3-b]triazole sulphoxide;
4-phenyl-7-oxothiazolo[3,2-b]triazole sulphoxide;
7-oxothiazolo[3,2-b]triazole sulphoxide;
7-oxothiaxolo[2,3-b]triazole S,S-dioxide;
4-methyl-7-oxothiazolo[2,3-b]triazole S,S-dioxide;
4-phenyl-7-oxothiazolo[3,2-b]traizole S,S-dioxide.
The compounds of formula (I) of the present invention, their synthetic intermediates and their processes of preparation are described in the following documents:
JP 07 09 84 89;
Khim. Geterotsilk. Soedin, 1967, p. 93;
J. Prakt. Chem., 318, 1976, p. 12;
Indian J. Heterocycl. Chem., 1995, 5 (2), p. 135;
Acta. Pol. Pharm., 1995, 52 (5), 415;
Heterocycl. Commun., 1995, 1 (4 ), 297;
Arch. Pharm. (Weinheim, Ger.) 1994, 327 (12), 825.
J. Am. Chem. Soc., 79, 1957, 2188;
Liebigs Ann. Chem., 744, 1971, 51;
J. Chem. Soc., 1949, 1160;
Bull. Chem., Soc. Chim. Belg., 75, 1966, 358.
The compound or compounds of formula (I) in accordance with the invention preferably represent from 0.0005 to 12% by weight approximately of the total weight of the dyeing composition and more preferably still from 0.005 to 6% by weight approximately of this weight.
The nature of the oxidation base or bases which can be used in the dyeing composition according to the invention is not critical. This or these oxidation bases are preferably chosen from para-phenylenediamines, bisphenylalkylenediamines, para-aminophenols, ortho-aminophenols, heterocyclic bases, and their addition salts with an acid.
Mention may in particular be made, among the para-phenylenediamines which can be used as oxidation bases in the dyeing compositon according to the invention, of the compounds corresponding to the following formula (II) and their addition salts with an acid: 
in which:
R5 represents a hydrogen atom or a C1-C4 alkyl, C1-C4 monohydroxyalkyl, C2-C4 polyhydroxyalkyl or (C1-C4)alkoxy(C1-C4)alkyl radical,
R6 represents a hydrogen atom or a C1-C4 alkyl, C1-C4 monohydroxyalkyl or C2-C4 polyhydroxyalkyl radical,
R7 represents a hydrogen atom, a halogen atom, such as a chlorine atom, or a C1-C4 alkyl, sulpho carboxyl, C1-C4 monohydroxyalkyl or C1-C4 hydroxyalkoxy radical,
R8 represents a hydrogen atom or a C1-C4 alkyl radical.
In the above formula (II) and when R7 is other than a hydrogen atom, then R5 and R6 preferably represent a hydrogen atom and R7 is preferably identical to R8 and, when R7 represents a halogen atom, then R5, R6 and R8 preferably represent a hydrogen atom.
Mention may more particularly be made, among the para-phenylenediamines of above formula (II), of para-phenylenediamine, para-tolulenediamine, 2-isopropyl-para-phenylenediamine, 2-(xcex2-hydroxyethyl)-para-phenylenediamine, 2-(xcex2-hydroxyethyloxy)-para-phenylenediamine, 2,6-dimethyl-para-phenylenediamine, 2,6-diethyl-para-phenylenediamine, 2,3-dimethyl-para-phenylenediamine, N,N-bis(xcex2-hydroxyethyl)-para-phenylenediamine, 4-amino-1-[(xcex2-methoxyethyl)amino]-benzene, 2-chloro-para-phenylenediamine, and their addition salts with an acid.
Mention may in particular be made, among the bisphenylalkylenediamines which can be used as oxidation bases in the dyeing composition according to the invention, of the compounds corresponding to the following formula (III) and their addtition salts with an acid: 
in which:
Q1 and Q2, which are identical or different, represent a hydroxyl or NHR12 radical in which R12 represents a hydrogen atom or C1-C4 alkyl radical,
R9 represents a hydrogen atom or a C1-C4 alkyl, C1-C4 monohydroxyalkyl, C2-C4 polyhydroxyalkyl or C1-C4 aminoalkyl radical in which the amino residue can be substituted,
R10 and R11, which are identical or different, represent a hydrogen or halogen atom or a C1-C4 alkyl radical,
W represents a radical taken from the group consisting of the following radicals:
xe2x80x94(CH2)nxe2x80x94; xe2x80x94(CH2)mxe2x80x94Oxe2x80x94(CH2)mxe2x80x94; xe2x80x94(CH2)mxe2x80x94CHOHxe2x80x94(CH2)mxe2x80x94 and 
in which n is an interger of between 0 and 8 inclusive and m is an integer of between 0 and 4 inclusive.
Mention may more particularly be made, among the bisphenylalkylenediamines of above formula (III), of N,Nxe2x80x2-bis(xcex2-hydroxyethyl)-N,Nxe2x80x2-bis(4-aminophenyl)-1,3-diamino-2-propanol, N,Nxe2x80x2-bis(xcex2-hydroxyethyl)-N,Nxe2x80x2-bis(4xe2x80x2-aminophenyl)ethylenediamine, N,Nxe2x80x2-bis(4-aminophenyl)tetramethylenediamine, N,Nxe2x80x2-bis(xcex2-hydroxyethyl)-N,Nxe2x80x2-bis(4-aminophenyl)tetramethylenediamine, N,Nxe2x80x2-bis(4-methylaminophenyl)tetramethylenediame, N,Nxe2x80x2-bis(ethyl)-N,Nxe2x80x2-bis(4xe2x80x2-amino-3xe2x80x2-methylphenyl)ethylenediamine, and their addition salts with an acid.
Among these bisphenylalkylenediamines of formula (III), N,Nxe2x80x2-bis(xcex2-hydroxyethyl)-N,Nxe2x80x2-bis(4xe2x80x2-aminophenyl)-1,3-diamino-2-propanol or one of its addition salts with an acid are particularly preferred.
Mention may in particular be made, among the para-aminophenols which can be used as oxidation bases in the dyeing composition according to the invention, of the comppunds corresponding to the following formula (IV) and their addition salts with an acid: 
in which:
R13 represents a hydrogen atom or a C1-C4 alkyl, C1-C4 monohydroxyalkyl, (C1-C4)alkoxy(C1-C4)alkyl or C1-C4 aminoalkyl radical,
R14 represents a hydrogen or fluorine atom or a C1-C4 alkyl, C1-C4 monohydroxyalkyl, C2-C4 polyhydroxyalkyl, C1-C4 aminoalkyl, C1-C4 cyanoalkyl or (C1-C4)alkoxy(C1-C4)alkyl radical,
it being understood that at least one of the R13 or R14 radicals represents a hydrogen atom.
Mention may more particularly be made, among the para-aminophenols of above formula (IV), of para-aminophenol, 4-amino-3-methylphenol, 4-amino-3-fluorophenol, 4-amino-3-(hydroxymethyl)phenol, 4-amino-2-methylphenol, 4-amino-2-(hydroxymethyl)phenol, 4-amino-2-(methoxymethyl)phenol, 4-amino-2-(amino-methyl)phenyl 4-amino-2-[(xcex2-hydroxyethyl)aminomethyl]-phenol, and their addition salts with an acid.
Mention may in particular be made, among the ortho-aminophenols which can be used as oxidation bases in the dyeing composition according to the invention, of 2-aminophenol, 2-amino-1-hydroxy-5-methylbenzene, 2-amino-1-hydroxy-6-methylbenzene, 5-acetamido-2-aminophenol, and their addition salts with an acid.
Mention may in particular be made, among the heterocyclic bases which can be used as oxidation bases in the dyeing composition according to the invention, of pyridine derivatives, pyrimidine derivatives, pyrazole derivatives, and their addition salts with an acid.
Mention may more particularly be made, among the pyridine derivatives, of the compounds disclosed, for example, in Patents GB 1,026,978 and GB 1,153,196, such as 2,5-diaminopyridine, and their addition salts with an acid.
Mention may more particularly be made, among the pyrimidine derivatives, of the compounds disclosed, for example, in German Patent DE 2,359,399 or Japanese Patents JP 88-169,571 and JP 91-333,495, such as 2,4,5,6-tetraaminopyrimidine, 4-hydroxy-2,5,6-triaminopyrimidine, and their addition salts with an acid.
Mention may more particularly be made, among the pyrazole derivatives, of the compounds disclosed in Patents DE 3,843,892 and DE 4,133,957 and Patent Applications WO 94/08969 and WO 94/08970, such as 4,5-diamino-1-methylpyrazole, 3,4-diaminopyrazole and 4,5-diamino-1-(4xe2x80x2-chlorobenzyl)pyrazole, and their addition salts with an acid.
According to the inention, the oxidation base or bases preferably represent from 0.0005 to 12% by weight approximately of the total weight of the dyeing composition and more preferably still from 0.005 to 6% by weight approximately of this weight.
The dyeing composition according to the invention can also include one or more additional couplers other than the compounds of formula (I) and/or one or more direct dyes, so as to vary or enrich with highlights the shades obtained with the oxidation bases.
The additional couplers which can be used in the composition according to the invention can be chosen from couplers conventionally used in oxidation dyeing and among which may in particular be mentioned meta-phenylenediamines, meta-aminophenols, meta-diphenols and heterocyclic couplers, such as, for example, indole derivatives or indoline derivatives, and their addition salts with an acid.
These couplers can in particular be chosen from 2-methyl-5-aminophenol, 5-N-(xcex2-hydroxyethyl)amino-2-methylphenol, 3-aminophenol, 1,3-dihydroxybenzene, 1,3-dihydroxy-2-methylbenzene, 4-chloro-1,3-dihydroxybenzene, 2,4-diamino-1-(xcex2-hydroxyethyloxy)benzene, 2-amino-4-(xcex2-hydroxyethyl)amino-1-methoxybenzene, 1,3-diaminobenzene, 1,3-bis(2,4-diaminophenyoxy)propane, sesamol, xcex1-naphthol, 6-hydroxyindole, 4-hydroxyindole, 4-hydroxy-N-methylindole, 6-hydroxyindoline, and their addition salts with an acid.
When they are present, these additional couplers preferably represent from 0.0005 to 5% by weight approximately of the total weight of the dyeing composition and more preferably still from 0.005 to 3% by weight approximately of this weight.
The addition salts with an acid of the oxidation base or bases and/or of the additonal couplers which can be used in the dyeing composition of the invention are chosen in particular from hydrochlorides, hydrobromides, sulphates and tartrates, lactates and acetates.
The medium appropriate for dyeing (or vehicle) is generally composed of water or of a mixture of water and of at least one organic solvent, in order to dissolve the compounds which would not be sufficiently soluble in water. Mention may be made, for example, as organic solvent, of lower C1-C4 alcohols, such as ethanol and isopropanol, glycerol, glycols and glycol ethers, such as 2-butoxyethanol, propylene glycol, propylene glycol monomethyl ether, diethylene glycol monoethyl ether and diethylene glycol monomethyl ether, and aromatic alcohols, such as benzyl alcohol or phenoxyethanol, the analogous products and their mixtures.
The solvents can be present in proportions preferably of between 1 and 40% by weight approximately with respect to the total weight of the dyeing composition and more preferably still between 5 and 30% by weight approximately.
The pH of the dyeing composition in accordance with the invention is generally between 3 and 12. It can be adjusted to the desired value by means of acidifying or basifying agents commonly used in dyeing keratinous fiber.
Mention may be made, among acidifying agents, by way of example, of inorganic or organic acids, such as hydrochloric acid, orthophosphoric acid, carboxylic acids, such as tartaric acid, citric acid or lactic acid, or sulphonic acids.
Mention may be made, among basifying agents, by way of example, of aqueous ammonia, alkaline carbonates, alkanolamines, such as mono-, di- and triethanolamines, and their derivatives, sodium hydroxide, potassium hydroxide and the compounds of following formula (V): 
in which R is a propylene residue optionally substituted by a hydroxyl group or a C1-C4 alkyl radical; and R15, R16, R17 and R18, which are identical or different, represent a hydrogen atom or a C1-C4 alkyl or C1-C4 hydroxyalkyl radical.
The dyeing composition according to the invention can also include various adjuvants conventionally used in hair dyeing compositions, such as anionic, cationic, non-ionic, amphoteric or zwitterionic surface-active agents or their mixtures, anionic, cationic, non-ionic, amphoteric or zwitterionic polymers or their mixtures, inorganic or organic thickening agents, antioxidizing agents, penetration agents, sequestering agents, fragrances, buffers, dispersing agents, conditioning agents, such as, for example, silicones, film-forming agents, preserving agents or opacifying agents.
Of course, a person skilled in the art will take care to choose the optional additional compound or compounds mentioned above so that the advantageous properties intrinsically attached to the dyeing composition according to the invention are not, or not substantially, detrimentally affected by the envisaged addition or additions.
The dyeing composition according to the invention can be provided in various forms, such as in the form of liquids, creams or gels, or in any other form appropriate for carrying out dyeing of keratinous fibers and in particular of human hair.
Another subject-matter of the invention is the use of the compounds of above formula (I) as coupler, in combination with at least one oxidation base, for the oxidation dyeing of keratinous fibers and in particular of human keratinous fibres, such as hair.
Another subject-matter of the invention is a process for the oxidation dyeing of keratinous fibres and in particular of human keratinous fibres, such as hair, employing the dyeing composition as defined above.
According to this process, at least one dyeing composition as defined above, is applied to the fibres, the colour being developed at acidic, neutral or alkaline pH using an oxidizing agent which is added only at the time of use to the dyeing composition or which is present in an oxidizing composition applied simultaneously or sequentially in a separate fashion.
According to a particularly preferred embodiment of the dyeing process according to the invention, the dyeing composition described above is mixed, at the time of use, with an oxidizing composition comprising, in a medium appropriate for dyeing, at least one oxidizing agent present in an amount sufficient to develop a colouring. The mixture obtained is subsequently applied to the keratinous fibres and is left to stand for 3 to 50 minutes approximately, preferably 5 to 30 minutes approximately, after which the hair is rinsed, washed with a shampoo, rinsed again and dried.
The oxidizing agent present in the oxidizing composition as defined above can be chosen from oxidizing agents conventionally used for the oxidation dyeing of keratinous fibres and among which may be mentioned hydrogen peroxide, urea hydrogen peroxide, alkali metal bromates, or persalts, such as perborates and persulphates. Hydrogen peroxide is particularly preferred.
The pH of the oxidizing composition including the oxidizing agent as defined above is such that, after mixing with the dyeing composition, the pH of the resulting composition applied to the keratinous fibres preferably varies between 3 and 12 approximately and more preferably still between 5 and 11. It is adjusted to the desired value by means of acidifying or basifying agents commonly used in dyeing keratinous fibres and as defined above.
The oxidizing composition as defined above can also include various adjuvants conventionally used in hair dyeing compositions and as defined above.
The composition which is finally applied to keratinous fibres can be provided in various forms, such as in the form of liquids, creams or gels, or in any other form appropriate for carrying out dyeing of keratinous fibres and in particular of human hair.
Another subject-matter of the invention is a dyeing multi-compartment device or kit or any other packaging system with several compartments, a first compartment of which includes the dyeing composition as defined above and a second compartment of which includes the oxidizing composition as defined above.
These devices can be equipped with a means allowing the desired mixture to be deposited on the hair, such as the devices disclosed in Patent FR-2,586,913 on behalf of the Applicant Company.